Jamie Wade catches up with FLSmidth's Automation general manager Darryl Stevens to discuss mineral sampling.
Jamie Wade: How has mineral sampling changed? What have been the most significant changes and developments that you've observed?
Darryl Stevens: There's significantly greater focus on ore quality today. A decade or more ago sampling was required, but it wasn't the prime target - production was. Today production is still the driver but at the correct quality.
Today, iron ore companies will not load ships unless they can sample. The risk of having ships rejected at port due to inferior ore is a growing reality.
In the early days of shipping iron ore the buyer accepted the sellers' quality report because they had limited quality control systems.
Today, both the buyer and the seller have installed sampling systems which provide comparison results to check the quality of shipped ore.
Both the buyer and the seller are also demanding greater functionality and uptime so sampling systems to ensure continuous control.
JW: Why is accurate sampling of ore important?
DS: It boils down to economics. An iron ore mine, for example, has an average life from 20 to 40 years so it's important to mine and sell that material at the optimum grade.
It's best practice to mine so stock piles have blended low and high grade ore to optimise the material sold.
Blending high grade with low grade where there is maybe five per cent or eight per cent difference in iron content can have a significant effect on the value of a mine towards the latter part of its life. Sampling provides the control to achieve these results.
JW: What are the key factors driving companies to adopt good sampling practices?
DS: Ore prices and volumes transported and their effect on profitability are two key factors driving good sampling practices. A sound understanding of sampling theory and its application provide mining companies with the best solutions. That's driven suppliers such as FLSmidth to provide advice and equipment that consistently conforms to industry standards.
Not all sampling devices conform to sampling theory and consequently may produce inaccurate or biased results that can influence the quality of samples taken. The decisions based on these erroneous results can have a strong economic impact.
JW: What are the benchmarks in engineering mechanical sampling systems to ensure quality control demands are met without compromising the productivity on a mine site?
DS: The clear benchmarks are conformance to international standards. Generally specific ISO [International Organization for Standardization] standards provide the guidelines to enable the correct selection of process and equipment to achieve a robust sampling system.
It is essential to engage designers and suppliers who have demonstrated expertise in sampling. Best practice involves taking a primary sample from a conveyor - or the primary area you're sampling from - and then degrees of subdivision both in sample volume and particle size to arrive at a sample for analysis which is representative of the original primary ore.
JW: In terms of mineral sampling what are the end users at port demanding in inspection and risk assessment?
DS: Given the volumes of ore moving through ports - loading and unloading - it's critical to have reliable, functional and low maintenance sampling systems. Hold ups and delays at port for any reason are extremely costly.
To minimise disruptions in this part of the supply chain there is an increasing trend towards automated sampling systems.
JW: What are the benefits of automated port sampling and quality control systems?
DS: There are significant cost savings to automating port sampling and quality control systems and much more reliability in the process with an automated sampling system.
Fully automated sampling systems combined with automated sample preparation and analysis provides not only savings in infrastructure cost but reductions in labour costs and potential OH&S considerations. The monitoring and control of automated systems can be performed from a single location.
JW: What key message or messages would you like to convey to the mining community about mineral sampling?
DS: The sampling process plays a big role in controlling exploration, mine development, ore processing and shipment. The whole mining process becomes optimised using correct sampling practice.
The use of sophisticated software to optimise stockyard and blending control requires quality data which can only be obtained from quality sampling.
The whole mining process becomes optimised using correct sampling practice.